On an existing wireless local area network (WLAN for short), a carrier sense multiple access (CSMA for short) with collision avoidance (CA for short) protocol is used at a Media Access Control (MAC for short) layer, to avoid a conflict that occurs on a channel when multiple network devices need to transmit data. In the CSMA/CA protocol, a network device that needs to send data contends for a channel.
Currently, to further improve a throughput of a WLAN, a scheduling mode is introduced in an 802.11 standard of Institute of Electrical and Electronics Engineers (IEEE for short), and a WLAN system becomes a high efficiency wireless local area network (HEW for short) system. In a WLAN system to which a scheduling mode is introduced, a basic service set (BSS for short) is used as a basic scheduling set, and when data transmission needs to be performed for a BSS, a channel is contended for according to the CSMA/CA protocol, which causes a relatively low success rate, and cannot meet a service requirement of the entire BSS.